GASB - Alder Springs, CA, USA

We operate broadband and borehole stations under the network code BK. The Berkeley Digital Seismic Network (BDSN) is a regional network of very broadband and strong motion seismic stations designed to monitor regional seismic activity as well as provide high quality data. The Berkeley borehole stations have borehole geophones or other seismic sensors and may have other geophysical instrumentation.

BARD is our GPS network for monitoring crustal deformation across the Pacific-North America plate boundary and in the San Francisco Bay Area for earthquake hazard reduction studies and rapid earthquake emergency response assessment

Network

Geology

Franciscan Complex Cretaceous and Jurassic sandstone

Borehole Conditions

The instruments are located in a steel and
concrete vault benched into a gentle hillside and
covered with soil overburden.
The concrete pier is covered with 4" of
insulation on the sides and 8" of insulation on
the top. The datalogger and supporting
equipment are in an adjacent room.

GPS Monument Description

Post fixed into the concrete that surrounds seismic vault. Post is reinforced by a concrete cylinder and three welded legs. The ends of the three legs were driven into the ground and filled in with cement.

GPS Data

Noise Analysis

GPS Data Quality

Completeness

Data completeness is defined both as "Completeness of observations" and "Cycle slips per observation". "Completeness of Obs." is the number of epochs in the final RINEX file normalized to the expected number. This percentage will go down if time is missing from the RINEX file. "Cycle slips per Obs." is the total number of detected cycle slip normalized to the total number of observations in the RINEX file. This number will increase as the receiver loses lock on satellites more frequently.

Previous Year

Lifetime

Multipath

The effects of multipath on the data are estimated by parameters for L1 and L2 (MP1 and MP2 respectively); see Estey and Meertens (GPS Solutions, 1999) for derivation. The daily value is the RMS of MP1 and MP2 throughout the day and for all satellites. Higher values indicate a greater prevalence and/or strength of multipathing, i.e. objects on the ground are providing multiple reflection pathways from the satellite to antenna.